Re: {Collins} Selenium diode for bias on 516F-2

[<entropycat@xxxxxxxxxxx>]

Greetings to Bob and the list:

   Thanks for the quick reference table.   I shall file it for future 
reference.   However, since the characteristics of this family of diodes are 
all similar except for the PIV, in order to save space and complication of 
my parts stock, I stock only the 1N4007, which I use for all purposes where 
1000 PIV or less is required.   These diodes are so cheap in bulk that it 
hardly seems worthwhile to stock the lower PIV values.

   Incidentally, I used a 1N4007 in my 516F-2 bias supply.   I had to add 
some additional series resistance owing to the lower forward drop of a 
silicon diode compared with a selenium, but this can be arrived at by trial 
and error, simply measuring the adjustment range of the bias voltage and 
comparing it with Collins spec.   I'd tell you what I came up with, but I 
don't remember, and I am too lazy to open up the supply to find out.   ;^)

   Just my $.02 worth.

73,
Jim T.
KB6GM
entropycat@xxxxxxxxxxx
"entropycat" copyright 2008 James K. Thorusen
All Rights Reserved

----- Original Message ----- 
From: Bob Hardie- W5UQ
To: John Hoffman
Cc: Collins Collins
Sent: Thursday, December 18, 2008 17:32
Subject: Re: {Collins} Selenium diode for bias on 516F-2


helpful info..
The 1N4001 through 1N400 family:
1N4001=   1A 50V Standard Rectifier
1N4002=   1A 100V Standard Rectifier
1N4003=   1A 200V Standard Rectifier
1N4004=   1A 400V Standard Rectifier
1N4005=   1A 600V Standard Rectifier
1N4006=   1A 800V Standard Rectifier
1N4007=   1A 1000V Standard Rectifier

These diodes are standard type diodes and vary in voltage.  Now you can see 
what you are going for.
A 1N4003 will work and the higher voltage diodes will work too.  It's just 
that the higher voltage diodes are not needed, but they will work.   So look 
in your parts boxes and go for it.

In the bias supply, it wouldn't hurt to put a surge resistor in series with 
the diode, at it's input.  Like a 0.82 ohm at 1 watt.  Higher resistances at 
higher wattage works too.  These supplies were made for 110 volts and we're 
using them on 125 volts so a little ballast doesn't hurt.
Bob